get_post_custom_keys

The timeline below displays how wordpress function get_post_custom_keys has changed across different WordPress versions. If a version is not listed, refer to the next available version below.

WordPress Version: 6.1

/**
 * Retrieves meta field names for a post.
 *
 * If there are no meta fields, then nothing (null) will be returned.
 *
 * @since 1.2.0
 *
 * @param int $post_id Optional. Post ID. Default is the ID of the global `$post`.
 * @return array|void Array of the keys, if retrieved.
 */
function get_post_custom_keys($post_id = 0)
{
    $custom = get_post_custom($post_id);
    if (!is_array($custom)) {
        return;
    }
    $keys = array_keys($custom);
    if ($keys) {
        return $keys;
    }
}

WordPress Version: 5.9

/**
 * Retrieve meta field names for a post.
 *
 * If there are no meta fields, then nothing (null) will be returned.
 *
 * @since 1.2.0
 *
 * @param int $post_id Optional. Post ID. Default is the ID of the global `$post`.
 * @return array|void Array of the keys, if retrieved.
 */
function get_post_custom_keys($post_id = 0)
{
    $custom = get_post_custom($post_id);
    if (!is_array($custom)) {
        return;
    }
    $keys = array_keys($custom);
    if ($keys) {
        return $keys;
    }
}

WordPress Version: 5.3

/**
 * Retrieve meta field names for a post.
 *
 * If there are no meta fields, then nothing (null) will be returned.
 *
 * @since 1.2.0
 *
 * @param int $post_id Optional. Post ID. Default is ID of the global $post.
 * @return array|void Array of the keys, if retrieved.
 */
function get_post_custom_keys($post_id = 0)
{
    $custom = get_post_custom($post_id);
    if (!is_array($custom)) {
        return;
    }
    $keys = array_keys($custom);
    if ($keys) {
        return $keys;
    }
}

WordPress Version: 4.3

/**
 * Retrieve meta field names for a post.
 *
 * If there are no meta fields, then nothing (null) will be returned.
 *
 * @since 1.2.0
 *
 * @param int $post_id Optional. Post ID. Default is ID of the global $post.
 * @return array|void Array of the keys, if retrieved.
 */
function get_post_custom_keys($post_id = 0)
{
    $custom = get_post_custom($post_id);
    if (!is_array($custom)) {
        return;
    }
    if ($keys = array_keys($custom)) {
        return $keys;
    }
}

WordPress Version: 4.0

/**
 * Retrieve meta field names for a post.
 *
 * If there are no meta fields, then nothing (null) will be returned.
 *
 * @since 1.2.0
 *
 * @param int $post_id Optional. Post ID. Default is ID of the global $post.
 * @return array|null Either array of the keys, or null if keys could not be
 *                    retrieved.
 */
function get_post_custom_keys($post_id = 0)
{
    $custom = get_post_custom($post_id);
    if (!is_array($custom)) {
        return;
    }
    if ($keys = array_keys($custom)) {
        return $keys;
    }
}

WordPress Version: 3.7

/**
 * Retrieve meta field names for a post.
 *
 * If there are no meta fields, then nothing (null) will be returned.
 *
 * @since 1.2.0
 * @link http://codex.wordpress.org/Function_Reference/get_post_custom_keys
 *
 * @param int $post_id post ID
 * @return array|null Either array of the keys, or null if keys could not be retrieved.
 */
function get_post_custom_keys($post_id = 0)
{
    $custom = get_post_custom($post_id);
    if (!is_array($custom)) {
        return;
    }
    if ($keys = array_keys($custom)) {
        return $keys;
    }
}